The majority of orthodontic treatment involves the movement of malpositioned teeth to desired positions within a patient's mouth. One common orthodontic treatment includes affixing small, slotted appliances, referred to as brackets, to the surface of a patient's teeth and then placing and securing an archwire in the bracket slots. The archwire is under tension, thus applying a force via the brackets to the teeth causing the teeth to shift positions. To ensure the teeth move in the desired manner, the brackets must be accurately positioned. For example, if a bracket is located too near the incisal or occlusal surface of a tooth relative to the adjacent brackets, the final position of that tooth can be unduly intruded, while if the bracket is located too near the gingival surface relative to the adjacent brackets, the final position of that tooth can be unduly extruded. While orthodontists are skilled with accurately placing the brackets, naked-eye placement tends to be limited to an accuracy of about +/−0.5 millimeters.
Complicating the positioning of the brackets is tooth visibility and accessibility. When teeth are severely crowded, accessing a tooth surface can be difficult. Further, loss of accessibility increases with each subsequent posterior tooth. Another problem is time, as the longer a patient sits in the dental chair, the more restless the patient can become which can negatively affect bracket placement accuracy.
There are many commonly available brackets. A combination of brackets is used for treatment, with different types of brackets for different teeth and for different treatment objectives. Furthermore, each orthodontist may have a preferred bracket prescription.
Traditionally, in order to install brackets on a patient's dental arch, measurements are taken of each tooth to determine the correct position for each bracket. Typically, these measurements are a naked eye approximation by the practitioner, via a measuring tool, or an external software program. The practitioner then manually places the brackets specifically for each tooth. Once the brackets are fixed in position, an archwire is run through the slots in the brackets and secured in place with elastomeric or metal ties or self-ligating bracket latches. Ideally, bracket locations do not change during treatment, however the archwires could be changed or adjusted, e.g., bent, as needed throughout treatment.
A solution to lengthy placement time and imprecise manual bracket placement involves indirect bonding. Indirect bonding utilizes a dental impression or scan of the patient's dental arches to replicate a patient's dentition. A plurality of brackets are positioned as desired on the replicated dentition. A dental template, which is a replication of the patient's arch that can be overlaid on the patient's physical arch, is fabricated with the bracket locations so that when the dental templates with the brackets engages the patient's dental arch, the brackets are properly aligned at the desired location on the desired teeth.